Late onset of dropped head syndrome following mantle radiation therapy for Hodgkin lymphoma

Abstract

Dropped head syndrome (DHS) is a rare condition, characterised by weakness of the cervical paraspinal muscles with sagging of the head. It is usually seen in association with neurological disorders and rarely can follow radiotherapy. We report a case of a 54-year-old man survivor of Hodgkin lymphoma (HL), who developed DHS 28 years after radiotherapy. He was referred to our department due to progressive weakness and atrophy of cervical paraspinal and shoulder girdle musculature. Physical and neurophysiological examination, electromyography and MRI confirmed the diagnosis of DHS. In the following years, there was no progression of symptoms.

Background

Dropped head syndrome (DHS) is a relative rare condition, with a broad differential diagnosis; it is characterised by severe weakness of the cervical paraspinal muscles, causing inability to extend the neck and resulting in gradual sagging of the head, that, in some cases, get the head totally flexed forward, a condition termed ‘chin-on-chest deformity’.^{1 2} DHS has significant implications on the health and the quality of life, which result seriously compromised. These patients usually experience neck pain, dysphagia and respiratory distress. This deformity causes, in addition, difficulties to maintain prolonged binocular frontal vision, thus impairing social interactions and an independent ambulation. Several conditions can cause DHS, including myasthenia gravis,³ motor neuron disease,^{4 5} congenital myopathies,⁶ chronic demyelinating polyneuropathy,⁷ Parkinson’s disease^{4 8} and isolated neck extensor myopathy.⁹ We present a case of DHS in a middle-aged man who had received high-dose whole-body irradiation for Hodgkin lymphoma (HL) 28 years before. DHS has been reported as a late complication of mantle irradiation in survivors of HL.^10–16 These patients develop a severe wasting of neck and shoulder girdle musculature, with DHS deformity. This condition requires a medical work-up and exclusion of treatable causes. In selected cases, surgery is contemplated.

Case presentation

A 54-year-old man was referred to our department for weakness and atrophy of cervical paraspinal and shoulder girdle musculature, as well as severe pain in the neck and shoulders. His neck deformity had been slowly progressive over the last 3–4 years, in absence of sensorimotor deficits in any extremities or respiratory complaints.

At 26 years of age, he was diagnosed with mediastinal HL (confirmed by hepatic, iliac and splenic biopsies) and treated with chemoradiotherapy which led to complete remission. Radiotherapy consisted of 40 sessions in 6 months of full-mantle irradiation after chemotherapy. Irradiation was early complicated by oesophagitis and hyperpigmentation. Finally, a splenectomy was performed. At the age of 37 he underwent to surgical removal of a laryngeal polyp, complicated by paralysis of the left vocal cord. He had not symptoms from any disturbances to the spine and neck for 28 years after mantle radiotherapy, until DHS gradually appeared when he was 54 years old.

Clinical examination revealed a dropped head in the forward-flexed position with an increase of the kyphotic angle of the cervicothoracic spine and difficulties to keep horizontal gaze. In our patient DHS appeared to be secondary to anterior cervical muscle contraction, as the deformity was completely reducible by the examiner. There was prominent bilateral hypotrophy and weakness of trapezius, sternocleidomastoid, scalene, splenius capitis and levator scapulae muscles (figure 1), with intact strength in shoulder girdle and limbs muscles (supraspinatus, deltoid and biceps brachii, figure 2). The patient presented hyperexcitability of patellar and Achilles tendon reflexes, normal sensation, coordination and cranial nerves. Dysphagia and dysarthria were absent. He did not report breathing difficulties or cramps.

Figure 1.

Severe hypotrophy and weakness of trapezius, sternocleidomastoid, scalene muscles, splenius capitis and levator scapulae can be observed in the patient, identifying a typical neuromuscular pattern of dropped head syndrome. The neck appears spindly and lacking in strength; spinal deformity can be observable as result of an increase of kyphotic angle and preposition of the head.

Figure 2.

The preserved strength in supraspinatus, deltoid, biceps and triceps brachii can be appreciated with tests against resistance.

Investigations

Laboratory investigations were unremarkable, except for serum creatine kinase level, which was slight elevated (258 IU/L). MRI and CT images of the neck revealed marked atrophy bilaterally in the trapezius, sternocleidomastoid and paraspinal muscles; however, MRI of the brain was normal and spinal cord MRI did not show a myelopathy. In addition, an MRI of the cervicobrachial plexus ruled out causes of compression of the cervical and brachial plexus or peripheral nerves. Whole-body positron emission tomography and CT did not show recurrences.

Nerve conduction studies, which included median and ulnar motor and median, ulnar, radial and sural sensory studies, were within normal limits, including absence of conduction blocks or any sign of neuropathy. Needle electromyography (EMG) showed absence of muscle activity at rest in all muscles examined and chronic neurogenic changes were found bilaterally in upper trapezius, sternocleidomastoid and extenders of the neck muscles during active contraction; the other muscles tested, including bilateral supraspinatus, infraspinatus, deltoid and biceps brachii muscles, demonstrated normal motor unit potential morphology and a full recruitment pattern. The patient refused to perform muscle biopsy.

Differential diagnosis

Despite initial electrodiagnostic findings were not specific, the clinical picture, laboratory studies, neuroimaging and EMG data helped us to exclude other causes of DHS in our patient. The absence of sensory symptoms with the radiological and electrophysiological findings ruled out the possibility of a plexopathy.

Furthermore, the monophasic progression with clinical deterioration and subsequent stabilisation allowed us to diagnose a DHS from radiotherapy.

Treatment

The patient wore a collar to keep the head raised. An intensive rehabilitation programme was followed, performing strengthening exercises of the paraspinal and extensors muscles, which lead to a better control of the head.

Outcome and follow-up

For 3 years the patient showed clinical stability, without further progression of symptoms or increase in dropping head.

Discussion

We report a case of late-onset DHS arisen 28 years after radiotherapy for HL associated with amyotrophy of bilateral trapezius, sternocleidomastoid and shoulder muscles. In our patient no causes other than remote whole-body irradiation therapy could be identified.

Radiation-induced DHS is a rare late-onset complication described in patients affected by HL, who are treated with mantle irradiation.^10–16 In this condition, symptoms can arise even many years after irradiation, and can vary widely from posterior neck and upper-back musculature hypotrophy to more extended involvements of the shoulder girdle, triceps and biceps brachii muscles, dysphagia and shortness of the breath. The stretch reflexes can be unelicitable or retained and sensory deficit had also been reported.^{10 11}

Our patient developed a peculiar localised form of radiation-induced DHS, in absence of spinal cord pathology on cervical MRI and without respiratory complaints, similar to patient 1 reported by Rowin and colleagues.¹¹ He had no disturbances for 28 years after mantle radiotherapy, until posterior neck muscle strength began to decline. He had to make considerable efforts to keep his head upright and came to our department because of a severe pain in the neck and shoulders.

Some authors stated that radiotherapy could determine a selective injury in the lower motor neurons of the spinal cord. Others suggest that spinal roots or peripheral nerves may be the primary sites of injury.¹⁰ However, the pathogenic mechanisms of radiation-induced DHS are still unknown.

Until now, it is not clear whether radiation-induced DHS is a myopathic or neuropathic disease. Histopathological studies present controversial results, with both myopathic and neurogenic patterns on EMG.^{10 11} Many authors reported a ‘radiation-induced myopathy’, with myopathic changes in the EMG and biopsy,^{15 16} others describe normal motor unit potential morphology and a full recruitment pattern¹¹ or fibre-type grouping, indicating chronic compensated neurogenic reinnervation, as well as reduced recruitment and abnormal spontaneous activity.¹¹

We suppose that late diagnosis from irradiation could confuse the interpretation of the biopsy. In fact, the histopathological picture of neurogenic and myopathic damage overlap in the late phase and it is very difficult to find out the cause of the damage in the affected muscles. Better, biopsy should be performed at the onset of the first symptoms in order to discover the mechanisms underlying the disease.

In any case, even in the absence of a muscle biopsy, slight elevated creatine kinase levels and the EMG pattern clearly neurogenic in all affected muscles, allowed us to rule out the possibility of a myopathy.

At difference with other differential diagnosis, DHS caused by radiotherapy shows no further progression of the disease with other related disability.

As described in our patient, a neuromuscular improvement can be possible through an intensive rehabilitative programme, including strengthening exercises of the neck muscles with a mild compensation of the cervicodorsal deformity. It must be taken into consideration that paraspinal muscles of the neck exert not only a biomechanical and support function, but moreover a proprioceptive role for postural balance, visual and vestibular system. Therefore, a walking training, balances flexibility exercises and aerobic training exercises should be included as necessary to improve mobility of cervicodorsal spine and quality of life of the patient. Prevention of progression can be managed by treating kyphosis and the degree of neck muscles retraction when a DHS diagnosis is early suspected.

Available treatment options include removable soft or hard collars and external orthotic device. Surgery can be considered in order to correct and stabilise the column, obtaining mechanical correction of DHS with neutral head alignment, when medical and physical treatment options have been exhausted.²

In conclusion, clinicians should be aware that isolated weakness could occur in cervical musculature of long-term Hodgkin disease survivors who had undergone mantle irradiation, even several years from radiotherapy. This condition is difficult to predict or avoid because of the long-time interval from irradiation. Lesions appear to be irreversible, like other complications of radiotherapy and markedly deteriorate the quality of life of affected patients. We agree with the current use of radiotherapy protocols that limit radiation dose in order to reduce early and late complications. Our case proves that radiation-induced DHS can gradually improve with early and appropriate muscle rehabilitation. Finally, greater recognition is required to institute appropriate intervention and rehabilitation in order to relieve the symptoms.

Learning points.

• Isolated weakness can occur in cervical musculature of long-term Hodgkin disease survivors who had undergone mantle irradiation even after more than 20 years from the radiotherapy.

• The differential diagnosis of dropped head syndrome (DHS) is broad and includes myasthenia gravis, motor neuron disease, congenital myopathy, chronic demyelinating polyneuropathy, Parkinson’s disease and isolated neck extensor myopathy; among all these, however, radiation induced DHS is the only one that usually does not show progression of symptoms.

• A neuromuscular improvement can be possible through an intensive rehabilitative programme including strengthening exercises of the neck muscles with a mild compensation of cervicodorsal deformity.